1. Field of the Invention
The present invention relates to an apparatus and method for generating a private key for an ID-based encryption system and a recording medium having a program recorded thereon for causing a computer to execute the method, and more specifically, to an apparatus and method for generating a private key for an ID-based encryption system using a method of calculating a discrete logarithm using a pre-computation table and a recording medium having a program recorded thereon for causing a computer to execute the method.
2. Discussion of Related Art
With recent development of computer technology and rapid expansion of communication networks, a security of computer-related resources and transmitted data is a big issue. An encryption based system is used as one alternative capable of resolving such a problem. An encryption system making a greatest contribution so far is a public key encryption system. In this traditional public key system, it is necessary to authenticate a user's public key in advance, and a problematic certificate should be discarded even though a validity period remains. Accordingly, there is a difficulty associated with management of a certificate of the public key. Therefore, an identity (ID)-based public key system based on personal identity (ID) has been proposed.
Technical approaches for implementing ID-based encryption include a scheme using pairing of an elliptic curve, a quadratic residue use scheme, a lattice use scheme, a trapdoor discrete logarithm (TDL) group use scheme, etc. The scheme using pairing of an elliptic curve is a scheme that is currently feasible, most universal, and actively studied. However, since this technology includes a pairing operation, an implementation method is very complex and much computing power is necessary.
On the other hand, the method of calculating a discrete logarithm using a TDL group may be implemented using an exponentiation operation relatively simpler than the pairing. In particular, an ID-based encryption system having a feasible level computing power and speed may be built using a pre-computation table. However, implementation of an ID-based encryption using TDL technology is considered to be theoretically possible and an actual implementation method is not disclosed. This means that the TDL technology has only been applied to solve a general discrete logarithm problem. Accordingly, to apply the TDL technology to an ID-based encryption system, a specific method should be proposed.
Related arts will be described in detail. US Patent Publication No. 2005-0097316 (Title of Invention: Digital signature method based on identification information of group members, and method of acquiring identification information of signed-group member, and digital signature system for performing digital signature based on identification information of group members) is directed to data encryption using a public key encryption scheme based on identification information of one or more members belonging to the same group. The present invention is directed to an algorithm for deriving a real private key in applying a method of calculating a discrete logarithm using a pre-computation table, and differs from the related art in a configuration.
Further, a digital signature apparatus having different personal private keys in a plurality of financial institutions while storing one personal private key in a remote financial service authentication system is disclosed in Korean Patent Laid-Open Publication No. 2001-0003569 (Title of Invention: Apparatus for generating digital signature based on private-key/public-key). The present invention is directed to an algorithm for deriving a real private key in applying a method of calculating a discrete logarithm using a pre-computation table, and differs from the related art in a configuration.